Method and device for emulating multiple RFID tags within a single mobile electronic device

ABSTRACT

The present invention provides a method for emulating multiple RFID tags for an RFID tag interrogation device, comprising the steps of storing one or more data sets, wherein each data set defines operational properties of an RFID tag, maintaining a list of said one or more data sets, indicating one data set in said list as active data set, receiving an interrogation from said RFID tag interrogation device, emulating, responsive to said interrogation, the operation of the RFID tag according to the active data set; and indicating another data set in said list as active data set. Also provided is a device for emulating multiple RFID tags for an RFID tag interrogation device, comprising a circuit configurable to emulate the operation of an RFID tag, a memory adapted for storing one or more data sets and a list of said one or more data sets, wherein each data set defines operational properties of an RFID tag, and wherein one data set in said list is indicated as active data set, a controller connected with said circuit and said memory, wherein said controller is adapted for being activated by an interrogation from said RFID tag interrogation device, for configuring said circuit according to said active data set, and for indicating another data set within said list as active data set. Furthermore a mobile electronic device comprising this device is provided.

The present invention relates to a method and a device for emulatingmultiple RFID tags in a single mobile electronic device. It particularlyrelates to the emulation of multiple RFID tags when said mobileelectronic device is powered down or powerless due to an exhaustedenergy supply.

So-called RFID (radio frequency identification) tags are transponderunits used e.g. in labeling goods, wirelessly readable smart cards andthe like. RFID tags may for example represent a railway ticket, atheatre ticket or a discount voucher.

An RFID tag stores information that can be read/written by an RFID taginterrogation device, or RFID tag reader/writer device, respectively.Such tags have to be available in all situations, as they may representthe above mentioned items which are necessary to a user, as railway orother transportation tickets or access control information for gainingaccess to offices and the like. That is, RFID tags may be used forreplacing conventional paper tickets/passports or physical keys.

A mobile electronic device can emulate the operation of an RFID tagusing a suitable electronic circuit and corresponding antenna. Thiselectronic circuit may be integrated into or be part of the circuitry ofthe mobile device itself. In these cases the circuitry of the mobiledevice provides the RFID functionality. The mobile electronic device can“store” multiple RFID tags, that is, store the data required to emulatesuch RFID tags. The emulation data comprises data defining the airinterface properties, like operating frequency, modulation, protocol andthe like, and data defining the actual data payload of the RFID tag. Thedata describing the RFID tag can then be made available to an RFID taginterrogation device through an RFID circuit and corresponding antenna.

Mobile electronic devices, however, are powered by energy supplies orbatteries with a rather limited capacity. Under certain circumstances itis also likely to occur that such a mobile electronic device is simplyshut down, e.g. while visiting an office building wherein the use ofmobile phones with cameras is prohibited.

As already mentioned, RFID tags have to function exactly as theirconventional counterparts, that is, tickets, keys or the like, in orderto be accepted by users. A conventional paper ticket or key, however, isnaturally not subjected to power failures. Therefore the RFID tags haveto be available even when the mobile electronic device is either powereddown by purpose or when its energy supply is exhausted, e.g. by a longtelephone call.

In order to be able to “store” multiple RFID tags within a mobileelectronic device, that is, the data required to emulate such tags, sucha mobile electronic device comprises a circuit that is configurable foremulating RFID tags. “Emulating” in the context of this invention meansthat the circuit is configured such that it behaves like the respectiveRFID tag. It will thus provide an air interface identical or at leastcompatible thereto, with respect to parameters like frequency,modulation, data rate and the like. Further it will also be enabled totransmit the same data payload, that is, data content as the RFID tag inquestion. Upon being interrogated by an RFID tag interrogation device(“tag reader”) the circuit will therefore behave exactly as the RFID tagto be emulated.

The circuit responsible for presenting such tags, however, does notcomprise any intelligent logic itself that would enable it to selectwhich one of a plurality of “stored” RFID tags should be presented if aninterrogation occurs. This selection, that is, the “loading” of the RFIDtag data into the circuit for configuration, can be handled by theprocessor of the mobile electronic device. However, in that case theabove mentioned problems will arise. If the mobile electronic device iswithout power, the selection could not be made. This will at best resultin the circuit staying configured to the last RFID tag it had emulated.

Without providing power to the mobile electronic device again the useris thus not able to access any other RFID tag stored within his device.If the device is shut down on purpose this will only provide a minordiscomfort to the user. Although it can be very annoying to first startthe device by entering a PIN or like to be enabled to open a door orenter an office, the user is not completely lost. However, if the energysupply of the device is exhausted, the user might become strandedwithout access to the other tags. He might be hindered from entering (orpossibly also leaving) his office or home, using a train or visiting atheatre.

As already mentioned, an important task for handling multiple RFID tagswithin an electronic device is the selection process. That is, theselection which one of the stored tags should be presented to aparticular RFID tag interrogation device. The appropriate tag could beselected using intelligence in the software of the electronic device,e.g. by identifying properties of the signal sent by the RFIDinterrogation device, or could be selected by the user through a userinterface thereof. However, for being able to use these approaches it ismandatory that the mobile device has power, which is not the case whenthe user has shut down the device by purpose, or when the energy supplyof the device is exhausted.

In order to ensure operability of the stored RFID tags under allcircumstances it is thus necessary to provide means for enabling a userto access all stored tags. There are two major problems associated withthis object. While it is in principle possible to provide dedicatedintelligence, that is, a suitable logic circuitry for performing thistask, this is not preferable in conjunction with RFID tags, as it wouldincrease the manufacturing costs in an unreasonable manner.

Another problem that may even be more important is the power supply ofsuch an intelligent logic circuitry. Due to the issues mentioned aboveit is not possible to rely only on the power supply of the device suchan RFID tag emulation circuit is comprised in. So-called passive RFIDtags do not comprise an internal power source; they are poweredcompletely by the electromagnetic interrogation signal. However, theenergy amount that can be supplied by such an interrogation signal isquite low. A complex circuitry that would be needed to enable aselection among a plurality of stored tags can not be powered by thislow energy amount.

The present invention provides a method and a device for solving theabove discussed problems with the selection, presentation/emulation ofRFID tags in a single mobile electronic device. With the invention auser is enabled to make use of any stored RFID tag, without beingrequired to first start his electronic device, and also in a state wherethe power supply of the device is exhausted.

The present invention provides means for handling multiple RFID tagswithin a single mobile electronic device. In order to enable suchmultiple RFID tag handling an electronic circuit can be used. Such anelectronic circuit can be powered by the mobile electronic device(active mode) or by the interrogation signal from the tag interrogationdevice (passive mode). The low power interrogation signal is notpowerful enough to provide power also to the mobile electronic device.

Therefore an interface ASIC (application specific integrated circuit)can be used as a power “wall” (separator of a self-sustaining powerdomain) in case power can not be provided by the mobile phone. Such aninterface ASIC would need to contain as little logic as possible, suchthat it can be powered by the current induced from the RFIDinterrogator.

However, current electronic circuits of this type can conventionallyonly cope with a single tag at a time, that is, the correct tag must be“downloaded” or programmed into the electronic circuit by the mobileelectronic device before the respective tag can be used. When the mobileelectronic device, e.g. a mobile phone is powered down or the batterypower is exhausted the electronic circuit is thus unable to decide whichof the stored RFID tags should be presented to an interrogation device,it will only be able to present the one it was last programmed with.When the phone battery is used up, maybe by a long phone call, the useris therefore unable to select which RFID tag to present. Usually theRFID tag used last will be the only one available. If for example theuser has just recently used a theatre ticket RFID tag, he cannot accesshis railway ticket within the phone and might become stranded withoutaccess to transportation.

The main problem is that the electronic RFID emulation circuit itself isunable to choose between stored tags, as it has little intelligencebuilt in. Such intelligence could be added to the electronic circuit byadding suitable circuitry, but this would naturally increase the costsand may increase the power requirements for the electronic circuitbeyond reasonable levels. The power consumption of the electroniccircuit, however, must not be higher than what can be provided by theinterrogation device, as otherwise the electronic circuit can notsuitably operate.

Currently, the electronic circuit can therefore only present the tag itwas last provided with by the mobile phone, thus the problem ofselecting other tags cannot be solved by the conventional technologywithout power being supplied by the mobile phone in some way.

It is therefore an object of the present invention to provide a methodand a device for enabling the emulation of multiple RFID tags in asingle mobile electronic device in powerless mode or powered down stateof the device.

According to one aspect a method for emulating multiple RFID tags for anRFID tag interrogation device is provided. The method is to be employedwith a device comprising a circuit configurable to emulate the operationof an RFID tag, and a memory. The method comprises the steps

-   -   storing one or more data sets, wherein each data set defines        operational properties of an RFID tag;    -   maintaining a list of said one or more data sets;    -   indicating one data set in said list as active data set;    -   receiving an interrogation from said RFID tag interrogation        device;    -   emulating, responsive to said interrogation, the operation of        the RFID tag defined by the active data set; and    -   indicating another data set in said list as active data set.        The inventive method enables the use of and access to multiple        RFID tags within a single mobile electronic device, particularly        in a powerless state of the mobile device.

In an exemplary embodiment the other data set is the subsequent data setin said list. When there is only one data set present, the subsequentdata set is this data set.

In an exemplary embodiment the RFID tag interrogation device compriseswriting capabilities, and the method further comprises the steps

-   -   receiving a write access from said RFID tag interrogation        device;    -   indicating, responsive to said write access, the previous data        set in said list as active data set; and    -   modifying the active data set in accordance with said write        access.        By this scheme a read-write-verify procedure is enabled, that        is, that tag is written to which was previously presented.        Tampering with other tags is efficiently prevented thereby.

In an exemplary embodiment the other data set is the precedent data setin said list. When there is only one data set present, the precedentdata set is this data set.

In an exemplary embodiment the method further comprises

indicating a pre-determined data set in said list as active data set.When performed within a mobile electronic device like a mobile phonecomprising additional processing capabilities and/or user input means,this enables either the mobile device or the user to indicate anotherdata set as active, that is, select the data set of said list which isto be presented first, for example upon initialization of said list. Thetag to be presented next to an interrogation device can so be selected,e.g. as long as the mobile device still has power, in order to speed upthe RFID tag presentation procedure at next use thereof. This enables tomake use of a “power down default” setting, which will be explained inconjunction with the following example embodiments of devices accordingto the invention.

In an exemplary embodiment, the method further comprises

-   -   re-arranging the order of the data sets in the list.        This enables to change the succession the stored RFID tags are        cycled through. The list can be given a new order, based on a        variety of parameters which will be explained later on. Changing        the order means that the position of one or more data sets in        the list is re-arranged.

In an exemplary embodiment the method further comprises

-   -   maintaining a value indicating the frequentness one or more of        said data sets have been indicated as active data sets;        wherein the re-arranging is performed in accordance with the        value.        As it may be likely that the most frequently used tag will        provide for the highest probability that it will be the one to        be presented during the next interrogation procedure, this can        help to speed up the latter.

In an exemplary embodiment the method further comprises

-   -   maintaining a usage history one or more data sets have been        indicated as active data sets;        wherein the re-arranging is performed in accordance with the        usage history.        This enables e.g. to build up a kind of FIFO (first in first        out) or LIFO (last in first out) scheme for the list to be        cycled through, e.g. for also speeding up the interrogation        procedure, e.g. by keeping track of which data set was        last/first used and re-ordering the list accordingly

In an exemplary embodiment the method further comprises

-   -   receiving a user input indicating one of the data sets; and    -   re-arranging the indicated data set within the list according to        the user input.        The user should advantageously be given the possibility to        re-arrange certain data sets within the list.

In an exemplary embodiment the method further comprises

-   -   determining a type of one or more data sets based on said        operational properties defined by said data sets;        wherein the re-arranging is performed in accordance with the        type.        The type of an RFID tag (read-only, writeable, single use,        multiple use, air interface standard etc.) is another parameter        suitable for re-arranging entries of the list.

In an exemplary embodiment the indicating of an active data setcomprises storing a pointer or updating a stored pointer, respectively,wherein the pointer indicates which one is the active data set. Using apointer, e.g. simply the number of the stored data set, is a convenientand simple way of indicating one data set as active. Updating can thenbe achieved by either increasing or decreasing the counter, which mayalso be called a counter then.

According to another aspect of the invention a computer program productis provided, comprising program code means for carrying out the methoddescribed above.

According to yet another aspect a computer program product is provided,comprising program code means stored on a computer readable medium forcarrying out the method described above.

According to still another aspect a computer data signal is provided,embodied in a carrier wave and representing a program comprising programcode means for carrying out the method described above.

According to a further aspect of the invention a device for emulatingmultiple RFID tags for an RFID tag interrogation device is provided. Thedevice comprises

-   -   a circuit configurable to emulate the operation of an RFID tag;    -   a memory adapted for storing one or more data sets and a list of        said one or more data sets, wherein each data set defines        operational properties of an RFID tag, and wherein one data set        in said list is indicated as active data set;    -   a controller connected with said circuit and said memory;        wherein said controller is adapted for being activated by an        interrogation from said RFID tag interrogation device, for        configuring said circuit according to said indicated data set,        and for indicating another data set within said list as active        data set.

This device enables to perform the above mentioned method of the presentinvention within a mobile electronic device. Circuit, memory andcontroller may be implemented by a suitable ASIC.

In an exemplary embodiment the other data set is the subsequent data setin said list.

In an exemplary embodiment the RFID tag interrogation device compriseswriting capabilities, and the controller is further adapted for beingactivated by a write access by the RFID tag interrogation device, forindicating the previous data set in the list as active data set, and formodifying the active data set in accordance with the write accessresponsive to the write access activation.

In an exemplary embodiment the previous data set is the precedent dataset in said list.

In an exemplary embodiment each data set is structured into

-   -   a header section defining air interface properties of an RFID        tag; and    -   a body section defining the data payload of the RFID tag.

In an exemplary embodiment the controller is adapted for performing theindicating of an active data set by storing a pointer in the memory orupdating a pointer stored in the memory, respectively, wherein thepointer indicates the active data set.

In an exemplary embodiment the inventive device may be implemented as aninterface Application Specific Integrated Circuit (ASIC). The memory andthe controller may so advantageously be integrated into a single ASIC,in order to save manufacturing costs and minimize the power consumption.

In an exemplary embodiment a device as described above is integratedinto a mobile electronic device, wherein the mobile electronic device isadapted for indicating a pre-determined data set as active data set.

In an exemplary embodiment a device as described above is integratedinto a mobile electronic device, wherein the mobile electronic device isadapted for re-arranging the order of said data sets in said list.

In an exemplary embodiment the mobile electronic device is adapted formaintaining a value indicating the frequentness said one or more of saiddata sets have been indicated as active data sets, and for performingsaid re-arranging in accordance with said value.

In an exemplary embodiment the mobile electronic device is adapted forone or more of said data sets have been indicated as active data sets,and for performing said re-arranging in accordance with said usagehistory.

In an exemplary embodiment the mobile electronic device comprises userinput means adapted for receiving a user input indicating one of saiddata sets, and wherein said mobile electronic device is adapted forperforming said re-arranging in accordance with said user input.

In an exemplary embodiment the mobile electronic device is adapted fordetermining a type of one or more of said data sets based on saidoperational properties defined by said data sets, and for performingsaid re-arranging in accordance with said type.

In an exemplary embodiment the mobile electronic device may have a“power down default” option. That is, a default setting can be chosensuch that during power down of the mobile device a pre-determined dataset is automatically indicated as active, in accordance with the defaultsetting. That way e.g. the user can pre-set the tag to be presentedfirst, which may help to speed up the interrogation procedure, even ifthe user forgot to change to the default data set prior to shutting downhis device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow diagram of an embodiment of the method according tothe invention;

FIG. 2 shows a flow diagram of another embodiment of the methodaccording to the invention;

FIG. 3 shows a schematic view of an embodiment of the device accordingto the invention; and

FIG. 4 shows a schematic view of the structure of the memory contents ofan embodiment of the inventive device.

DETAILED DESCRIPTION OF THE INVENTION

The device of the present invention must be able to store multiple tagssuch that it has access to all the possible tags without having to relyon the mobile phone memory or processor. To decide which tag to presentto an interrogation device a counter or pointer may be used to cyclethrough the available tags.

Referring to the example of a user wishing to access his railway ticketwhich has been mentioned in the introduction, a user may have toactivate the interrogation device up to three times but the correct tagwould be presented and the user will have access to his stored tags.

This arrangement, that is, simply cycling through the available tags inorder to be able to access all tags, requires minimal extra processingability and power consumption over a basic electronic circuit (e.g.interface ASIC) as all the (initial) setup can be performed by themobile phone processor, the pointer management being the only extraadministration required in the electronic circuit.

The pointer is used to indicate which of the stored tags is to bepresented to an interrogation device upon interrogation of theelectronic circuit. The pointer is set to refer to the next tag, makingthis tag the “active tag”, each time the electronic circuit is activatedby a read operation. In this way the tag to be presented or the activetag, respectively, is cycled through the available tags, giving accessto each one in turn. Upon a write operation the pointer may be moved tothe previous tag, before performing the actual writing operation, sothat the tag written to is the one which was previously read. In thisway a read-write-verify operation can be handled without disruptingother stored tags.

However, this depends on when the pointer increment takes place. Thefollowing exemplary embodiments are also possible with the invention. AREAD+MODIFY operation may be performed with increment of thepointer/counter after completion. Or the increment is performed onlyafter a WRITE operation was done or after it was discovered that noWRITE operation is to be performed. In those cases no “setting back” ofthe pointer needs to be done.

It is to be noted that the pointer must of course be non-volatile duringpower removal.

A list is used to locate the multiple tags within the memory. The liststores the number of available tags together with access data like thestart position in memory of each tag, and the length of payload datathereof. In an embodiment, this list is used in conjunction with thepointer in order to locate the RFID tag that is to be accessed.

In embodiments wherein the tag header is stored, it may be of fixedsize, and it is used to store the air interface settings required by thetag to be emulated. That is, the properties of the air interface of therespective tag to be emulated are stored within the header. Theseproperties may include operating frequency, transmission rate, supportedfunctionality, modulation form and other parameters associated with theair interface. The electronic circuit is thus enabled to present the tagpayload data in the suitable protocol required by the interrogationdevice.

In this way tags of different RFID standards/protocols etc. can beaccommodated within the same electronic circuit without a necessaryintervention by the mobile phone. Upon activation of the electroniccircuit the settings stored for the current RFID tag are used toconfigure the electronic circuit to adhere to the required standard.

In alternative embodiments of the invention the electronic circuit canalso make use of only one RFID tag air interface format or standard. Inthat case the header section may even be omitted completely in the datasets, as the air interface is then pre-determined by the fixed usedstandard. As there are a number of standards available it will, however,be advantageous to be able to adapt to different standards within in onedevice.

The length of data stored for that tag and the maximum length of thedata is also stored in the tag header. A small amount of free space canbe allocated at the end of data payload section to allow for expansionof the tag data by a write access from a writing-capable interrogationdevice.

The mobile phone can select the default tag to be presented by settingthe pointer to refer to the appropriate data set as long as the mobilephone is powered.

Allowing a user to store multiple tags within an ASIC comprises thepossibility of storing multiple copies of the same tag within theinterface ASIC. This could cause a security problem when a monetaryvalue is attached to the tag, e.g., multiple copies of a railway ticketwhich is never invalidated by an interrogation device.

To address this issue the mobile phone must verify that all the tagsstored within the device are unique. However, a solution for thisproblem is simple and cheap, and fits in with existing RFID schemes.

In FIG. 1 a basic embodiment of the method of the present invention isdepicted. After starting in step 102 one ore more data sets are storedwithin a memory in step 104, a list of the data sets is maintained(initially built and later on updated accordingly) in step 106 and oneof the data sets is indicated as active (step 108). All of these datasets define the operational properties of RFID tags, which isillustrated in more detail in FIG. 3. The term “operational properties”of an RFID tag is to be understood, in the context of the presentinvention, as representing all parameters necessary for emulating thebehavior of the RFID tag in question.

Depending on the actual implementation of the corresponding electroniccircuit, this will usually include all air interface properties(frequency, modulation pattern etc.), however in alternative embodimentsthe operational properties may be reduced to the actual payload, if theair interface is fixed to one format/standard, as mentioned earlier.

Preferably, these properties include two main sections. A first datasection is related to the air interface of the RFID tag. That is,parameters like operating frequency, modulation form, protocol used andthe like are defined by this section. The second section is related tothe data content of the tag itself, that is, the data payload thereof.As already mentioned there are various uses for RFID tags. Depending onthe specific application of a particular RFID tag the payload maycomprise identification data for identifying a certain person, e.g. foraccess control, or data representing a railway or theatre ticket, orother known RFID tag contents.

In case the respective tag is also writable, that is, its data contentcan be altered by a writing capable interrogation device, there may alsobe provided a reserved free section. This provides for a certain amountof additional data that can be written to the respective tag. Or inother words, the reserved free space determines how much data may beadded to a certain tag.

The list of the data sets comprises a plurality of entries, each beingassociated with one of the stored RFID tags. Each entry contains atleast a unique identifier, which may be a number, a starting positionwithin the memory and a length of the respective data set. Optionallyalso a maximum allowed length for the tag payload data can be included.The latter relates to tags that are writeable, and wherein the payloaddata are not to exceed a predefined total length within the memory. Thelist of data sets is an ordered list, that is, the entries are arrangedin a successive manner. In certain embodiments, this is required toenable the inventive device to re-set the pointer referring to one dataset entry within the list without having to implement too complex logicfor choosing which entry is the “subsequent” or “preceding” entry.

The invention does also work with only a single stored RFID tag, forexample when currently only one RFID is stored, although there willusually be more than one. However, there may be situations wherecurrently only one tag is present. In the situation where only one dataset is present, the terms “subsequent” or “precedent” are to beunderstood as referring to that same data set.

In step 110 an interrogation by an RFID tag interrogation device isreceived (this step is looped or repeated until an interrogationoccurs). That is, the circuit of the inventive device is being activatedor powered by the interrogation signal. Upon being interrogated thecircuit is (re-)configured (step 112) according to the data set that isindicated as active, e.g. in one embodiment referred to by a pointer.The circuit is now ready to emulate the respective tag defined by theactive data set.

In step 114 another data set is indicated as active, e.g. the pointer isnow set forth. “Another” will, in the context of the present invention,usually mean the data set that is the subsequent data set within thelist. However the data set which is indicated as active can, in otherembodiments, also be chosen in a different manner, e.g. by tag type,frequentness of tag use, tag usage history (FIFO, LIFO order) etc.

It is to be noted that “subsequent”/“preceding” only refer to thedirection in which the list is processed. This is not to be understoodas restricting the present invention. For example, if the abovementioned indicators of data sets are numbers (1, 2, 3, . . . ) orpossibly letters (a, b, c, . . . ) the list can either be processed indescending order (1→2→3→ . . . /a→b→c→ . . . ) or in ascending order.The indicators are preferably as short as possible. This is required tominimize the administration effort when (re-)setting the pointer.

In step 116 the configured circuit is read out by the RFID taginterrogation device, shown in dashed lines. This step can also occurbetween steps 112 and 114, or together with step 110. As this step 116is not part of this invention itself it is shown in dashed lines here.

The process can then return to step 110 and be continued. That willusually mean that the mobile electronic device comprising the inventivedevice is removed from the operational range of the RFID taginterrogation device. If the desired tag has already been presenteduntil now, the process can be concluded here. However, if the tag wasnot the one the user wanted to present, the user has to cycle throughthe method steps 110 to 116 again at least once. Even in the worst casethe user has to repeat the procedure only as many times as there aretags stored in his mobile electronic device, e.g. five times in case offive different RFID tags.

It is also to be noted that the previous and following description willmainly focus on an embodiment where a list and a pointer referring tothe active data set will be used in maintaining the list. However, theinvention is not limited to this exemplary embodiment, the active dataset can be marked also by other means, e.g. by an “active” flag in eachdata set header or like.

While the above described embodiment according to the method of theinvention is also useful in cases where the mobile electronic device hasbeen shut down on purpose, the invention is particularly advantageouswhen the mobile device is powerless due to insufficient batteries, andthe user is thus unable to provide it with power. Instead of gettingstuck without access to important RFID tags as with the conventionaltechnology, he is able to perform a kind of “emergency” tag read-outprocedure by introducing his mobile device to an RFID tag interrogationdevice as many times as required. Under all circumstances he will beable to finally present the “right” RFID tag.

FIG. 2 shows a variation according to an advanced embodiment of theinventive method. The procedure starts in step 202, and it is assumedhere that the preliminary step 104 according to FIG. 1 has already beenperformed. Although this is not necessary for this embodiment to work,the complete procedure according to FIG. 1 may already have beenperformed. In step 204 a write access is received from a writing capableRFID tag interrogation device (or this step is repeated until such writeaccess occurred). In step 206 the previously active data set isindicated as active, e.g. the pointer is set back, that is, set to referto the preceding data set in the list. It is to be noted that thisparticular succession is required. As the present invention is the mostuseful in cases where the mobile electronic device in question iswithout power, the user is unable to recognize which tag is currentlyused to configure the emulation circuit, e.g. through the display of themobile device.

While this is irrelevant with pure read access, it may be very relevantfor write accesses. It should be apparent that any write access to thewrong tag is to be prevented. There are known techniques for avoidingthat a tag is accidentally overwritten with false content, like the useof session IDs and the like. These techniques are per se known and shalltherefore not be detailed further herein. However, the user should beprovided with a possibility to recognize which tag is written to.Therefore the invention uses the described succession, in order toenable a read-write-verify procedure. For example in case of a railwayticket comprising a monetary value corresponding to three rides the userwould first cycle through the tags until the railway RFID tag shows up.

This should be indicated by the tag interrogation device, a tellermachine or like, probably comprising a display. The interrogation devicecould now present the user a choice like “debit current ride from tag?”.Upon acknowledgment by the user the teller machine or like could nowre-write the corresponding tag content. Finally, the user can use theinterrogation device again, by simply presenting his mobile deviceagain, for verifying that the debit procedure has been performedcorrectly. For all read accesses the method as described in conjunctionwith FIG. 1 can be used.

However, it is to be noted that this depends on when the pointerincrement takes place. As mentioned earlier the following examples couldalso be possible: a READ+MODIFY with increment at the end. Or theincrement takes only place after a WRITE was done or after it wasdiscovered that no WRITE needs to be done. In those cases no “settingback” of the pointer needs to be done.

FIG. 3 is a schematic diagram of a mobile electronic device comprisingthe inventive multiple tag emulation device. The mobile electronicdevice is depicted here as a mobile phone 10, however, the invention mayas well be applied to any other mobile electronic device like an mp3player, a smartphone, PDA, notebook computer or like. A circuit 2 isprovided, which may be configured to emulate the behavior of a certainRFID tag. Such circuit can be implemented as an application specificcircuit ASIC.

A memory 4 is provided for storing at least two data sets, wherein eachdata set defines the properties of an RFID tag. As has been describedbefore, this refers to the air interface parameters as well as theactual data payload of such an RFID tag. A controller 6 is connectedwith the memory 4 and the circuit 2. The contents of the memory 4 havealready been described earlier; for a more detailed description see alsoFIG. 4. The controller 6 is adapted for being provided power by saidcircuit 2, upon an interrogation procedure by an RFID tag interrogationdevice 8. The RFID interrogation signal 12 will then activate thecircuit 2, enabling it to power also the controller 6.

Preferably the inventive device is implemented as an ApplicationSpecific Integrated Circuit (ASIC), and the memory and controller areintegrated into the ASIC, which is advantageous with respect to costsand power saving.

As already described in conjunction with the inventive method thecontroller 6 will, upon an interrogation, configure the circuit 2according to one of the stored RFID tags in memory 4. In order toperform this action the controller 6 has to read the pointer stored inthe memory 4, which refers to one of the data sets in the memory 4. Thecontroller 6 is thus enabled to access the respective data set, in orderto use the properties defined by the data set to configure the circuit2.

When the circuit is (re-)configured according to the data set inquestion, an RF response signal 14 will be generated and emitted to theRFID tag interrogation device 8. Depending on the actual type ofresponse signal 14, which depends on the properties defined by the dataset, the RFID tag interrogation device 8 will accept the response ornot. The RFID tag interrogation device 8 may e.g. be some access controldevice, wherein the appropriate response will function as a key.

The controller 6 is further adapted to re-set the pointer in memory 4 tothe subsequent entry within the list of data sets. If the responsesignal 14 was not the appropriate one, this enables the user of themobile device to remove it from the RFID tag interrogation device 8, andto introduce it thereto again. The device 10 comprising the inventiveRFID tag emulation device can so be used to present all stored tags,without relying on an internal power source.

In advanced embodiments (not shown), the mobile device 10 can alsocomprise an internal power source, a central processor, a display anduser input means. With these conventional means, which shall thereforenot be described in detail here, the user and/or the mobile device areenabled to manipulate both the pointer as well as the list of data sets.For example the mobile device could keep track of the frequentness acertain stored RFID tag is used, and re-arrange the position of thecorresponding data set within the list, or at least re-set the pointerto refer to that particular data set.

In this manner the chances would be improved that the first RFID tag theemulation circuit 2 has been configured to emulate is the one requiredwhen the user introduces his mobile device to an interrogation devicethe next time. The list, which is an ordered list of stored RFID tags ortheir properties, respectively, can be re-ordered/re-arranged accordingto such parameters as the frequentness a certain tag is used. Otherparameters to be used for this re-arranging include a usage history ofthe tags, that is, which one was used first/last, or also the type ofcertain RFID tag (read-only, writable, size of data content/payload,standard of air interface etc.). That is, any parameter that can be usedto re-set the pointer and/or re-arrange the list in order to improve thechances the most probable RFID tags are emulated first, can be used inthis context. For example FIFO (first in first out) or LIFO (last infirst out) schemes can be implemented.

In an embodiment of the present invention it is also possible to providethe user with means for manually re-setting the pointer and/orre-arranging the succession of data sets. Depending on the complexity ofthe user interface of the respective mobile device there are manypossibilities to achieve this. In a most simple way, the user couldindicate one of the data sets, and the mobile device would then moveup/down this data set one position, put it at either end of the list, orset the pointer to refer to that data set. Other possible ways ofachieving such list arranging/re-setting of the pointer should beapparent to an artisan, and are included within the scope of thisinvention.

FIG. 4 shows a structure of the memory used in devices and methods ofthe present invention. The memory 4 (see also FIG. 3) in this casestores 3 data sets 26, referring to tags 1, 2 and 3. The memory furtherstores a list 24, which comprises an ordered list of the stored datasets 26. As has been shown on the right side of this figure, the listcomprises for each tag at least an indicator (e.g. a number), thestarting position of the tag within the memory 4, and the length of thetag (optionally also the maximum length of writeable tags). Startingposition and length are parameters necessary to access the respectivedata necessary to configure the tag emulation circuit. That is, the listcomprises all required management information enabling the controller toappropriately handle the tags.

Each data set 26 comprises a header section 28, a body section 30 andoptionally a free section 32. The header section 28 defines theproperties of the air interface of an RFID tag, that is, parameters likefrequency, modulation, data rate, used protocol and the like. In thebody section 30 the actual data content is stored, e.g. information of arailway ticket, access control or like. In this data section also datacan be written/overwritten, in case the tag is writeable. In case theRFID tag described by the data set 26 is a tag the data content of whichmay be written to, the reserved free section 32 can be provided.

This enables the data content to be increased with respect to its sizein case a write access occurs. The tag can be expanded during a writingoperation without overwriting other tags. However, the dimension of thisfree section 32 also limits the maximum amount of data that can bewritten to this tag data set.

The invention claimed is:
 1. Method comprising causing one or more datasets to be stored, wherein each data set defines operational properties,including a data payload, of a radio frequency identification (RFID)tag; causing a list of said one or more data sets to be maintained;indicating a first data set in said list as an active data set bycausing a pointer indicating said first data set to be stored or bycausing a previously stored pointer to be updated so as to indicate saidfirst data set, the first data set defining a first data payload;receiving an interrogation from an RFID tag interrogation device;causing, responsive to said interrogation, the operation of the RFID tagto be emulated according to the active data set; and following theindication of the first data set as the active data set, automaticallyindicating a second data set in said list as the active data set bycausing the pointer to be updated to indicate the second data set, thesecond data set defining a second data payload which is different fromthe first data payload; wherein only one data set in the list isindicated as the active data set at a time.
 2. Method according to claim1, wherein said second data set is the subsequent data set in said list.3. Method according to claim 1, wherein said RFID tag interrogationdevice comprises writing capabilities, further comprising: receiving awrite access from said RFID tag interrogation device; indicating,responsive to said write access, the previous data set in said list asactive data set; and causing the active data set to be modified inaccordance with said write access.
 4. Method according to claim 3,wherein said previous data set is the precedent data set in said list.5. Method according to claim 1, further comprising: indicating apre-determined data set in said list as active data set.
 6. Methodaccording to claim 1, further comprising: causing the order of said datasets in said list to be rearranged.
 7. Method according to claim 6,further comprising: causing a value indicating the frequentness one ormore of said data sets have been active data sets to be maintained;wherein said re-arranging is caused to be performed in accordance withsaid value.
 8. Method according to claim 6, further comprising: causinga usage history comprising when the one or more data sets have beenactive data sets to be maintained; wherein said re-arranging isperformed in accordance with said usage history.
 9. Method according toclaim 6, further comprising: receiving a user input indicating one ofsaid data sets; and causing said indicated data set to be rearrangedwithin said list according to said user input.
 10. Method according toclaim 6, further comprising: determining a type of one or more data setsbased on said operational properties defined by said data sets; andcausing the order of said data sets to be rearranged in accordance withsaid type of one or more data sets.
 11. Computer program productcomprising a non-transitory computer readable storage medium containingprogram code portions, the program code portions being configured to,upon execution, cause an apparatus to at least: cause storage of one ormore data sets, wherein each data set defines operational properties,including a data payload, of a radio frequency identification (RFID)tag; cause a list of said one or more data sets to be maintained;indicate a first data set in said list as an active data set by causinga pointer indicating said first dataset to be stored or by causing apreviously stored pointer to be updated so as to indicate said firstdata set, the first data set including a first data payload; receive aninterrogation from an RFID tag interrogation device; cause, responsiveto said interrogation, the operation of the RFID tag to be emulatedaccording to the active data set; and following the indication of thefirst data set as the active data set, automatically indicate a seconddata set in said list as the active data set by causing the pointer tobe updated to indicate the second data set, the second data setincluding a second data payload which is different from the first datapayload; wherein only one data set in the list is indicated as theactive data set at a time.
 12. Computer program product according toclaim 11, wherein said program code portions are executed in a processorin a computer or network device.
 13. An apparatus, comprising: a memoryconfigured to store one or more data sets and a list of said one or moredata sets, wherein each data set defines operational properties,including a data payload, of a radio frequency identification (RFID)tag, and wherein a stored pointer indicates a first data set in saidlist as an active data set, the first data set including a first datapayload; an RFID tag interrogation device; a controller connected withsaid memory, wherein said controller is configured to: be activated byan interrogation from the RFID tag interrogation device, configure acircuit that is configured to emulate operations of an RFID tagaccording to said active data set, and following the indication of thefirst data set as the active data set, automatically indicate a seconddata set within said list as the active data set by causing the storedpointer to be updated to indicate the second data set, the second dataset including a second data payload which is different from the firstdata payload; wherein only one data set in the list is indicated as theactive data set at a time.
 14. Apparatus according to claim 13, whereinsaid second data set is the subsequent data set in said list. 15.Apparatus according to claim 13, wherein said RFID tag interrogationdevice comprises writing capabilities, and wherein said controller isfurther configured to: be activated by a write access by said RFID taginterrogation device, and indicate the previous data set in said list asactive data set, and cause the active data set to be modified inaccordance with said write access, responsive to said write accessactivation.
 16. Apparatus according to claim 15, wherein said previousdata set is the precedent data set in said list.
 17. Apparatus accordingto claim 13, wherein each data set comprises: a header section definingair interface properties of the RFID tag; and a body section definingthe data payload of said RFID tag.
 18. Apparatus according to claim 13,implemented as an interface Application Specific Integrated Circuit(ASIC).
 19. Mobile electronic device, comprising an apparatus accordingto claim 13, wherein said mobile electronic device is configured tocause a pre-determined data set to be indicated as active data set. 20.Mobile electronic device, comprising a device according to claim 13,wherein said mobile electronic device is configured to cause the orderof said data sets to be rearranged in said list.
 21. Mobile electronicdevice according to claim 20, wherein said mobile electronic device isconfigured to maintain a value indicating the frequentness said one ormore of said data sets have been indicated as active data sets, and tocause said re-arranging in accordance with said value.
 22. Mobileelectronic device according to claim 20, wherein said mobile electronicdevice is configured to cause a usage history comprising when the one ormore of said data sets have been indicated as active data sets to bemaintained, and to cause said re-arranging in accordance with said usagehistory.
 23. Mobile electronic device according to 20, wherein saidmobile electronic device comprises user input means configured toreceive a user input indicating one of said data sets, and wherein saidmobile electronic device is configured to cause said re-arranging inaccordance with said user input.
 24. Mobile electronic device accordingto claim 20, wherein said mobile electronic device is configured tocause a type of one or more of said data sets to be determined based onsaid operational properties defined by said data sets, and to cause saidre-arranging in accordance with said type.
 25. An apparatus comprising:a memory; a radio frequency identification (RFID) tag interrogationdevice; a controller configured to be activated by an interrogation fromthe RFID tag interrogation device, said controller also configured toreceive an indication from the memory of an active data set from among alist of one or more data sets stored by the memory, said indicationcomprising a stored pointer indicating a first data set as the activedata set, said controller further configured to configure a circuit thatis operable to emulate the operation of an RFID tag according to theactive data set that defines operational parameters, including a firstdata payload, of an RFID tag, said controller further configured to,following receiving the indication of the first data set as the activedata set, automatically indicate a second data set within said list asthe active data set by causing the stored pointer to be updated toindicate the second data set, wherein the second data set includes asecond data payload which is different from the first data payload andonly one data set in the list is indicated as the active data set at atime.
 26. An apparatus according to claim 25, wherein said second dataset is the subsequent data set in said list.
 27. An apparatus accordingto claim 25, wherein said RFID tag interrogation device compriseswriting capabilities, and wherein said controller is further configuredto: be activated by a write access by said RFID tag interrogationdevice, indicate the previous data set in said list as active data set,and cause the active data set to be modified in accordance with saidwrite access, responsive to said write access activation.
 28. Anapparatus according to claim 27, wherein said previous data set is theprecedent data set in said list.
 29. An apparatus according to claim 25,wherein each data set comprises: a header section defining air interfaceproperties of an RFID tag; and a body section defining the data payloadof said RFID tag.
 30. An apparatus according to claim 25, implemented asan interface Application Specific Integrated Circuit (ASIC).